On July 19, Melissa Tuffner was found unconscious on a street in Glew, an hour away from Buenos Aires, the Argentine capital. Three days later, she died from an internal bleeding caused by severe beating. It's still unclear who murdered her and why.

Some people, like her brother, are expressing their pain on Facebook: "I woke up with the illusion that all this was just a nightmare, but it isn't the case. ... I won't ever get used to not seeing you every day. ... I love you and I miss you."

The update, which was posted as a joke by Tuffner's friend, read, "Bye, bye, going out with my boyfriend." But Tuffner had never mentioned her boyfriend on any of her previous posts on social media, so everyone commented with surprise. One of her friends later said that a common friend had logged into her account and updated her status as a joke.

Tuffner posted a lot of photos of her on her profile, many of which showed her smiling.

Her friends are posting messages thinking about her smile: "Sometimes I wonder why are we here in this life, when people with a bright future, full of life, with a beautiful smile on their faces, leave in one second, tearing apart a lovely family."

Now everybody is looking for witnesses to find out what actually happened before Tuffner was lying unconscious on the street on July 19. Local police has asked for anyone with information to reach out to them.